1. Technical Field of the Invention
The present invention relates to a monitor for monitoring a periphery of a vehicle with an optical radar device wherein light waves emitted from the optical radar device scan an object in the horizontal direction, and light waves reflected on the object and returned to the optical radar device are received, so that a distance from the optical radar device to the object and a direction to the object can be detected. More particularly, the present invention relates to a monitor for monitoring the periphery of a vehicle characterized in that only one set of monitoring devices can monitor a wide area in the periphery of a vehicle.
2. Description of the Related Art
A conventional optical radar device used for this type monitor for monitoring a periphery of a vehicle is disclosed, for example, in JP-A-8-122061, which is operated in such a manner that an object is scanned with light waves in the horizontal direction so that the object can be detected in a wide range.
According to the above patent publication, there is disclosed an arrangement including a rotary shaft of a rotary driving means for conducting scanning and an optical system of a light sending means, wherein the rotary shaft and the optical system are arranged on the same axis.
When the monitor for monitoring the periphery of a vehicle is incorporated into the vehicle, space for housing the monitor is usually limited by structures and designs of the vehicle itself. Especially when the monitor is designed in such a manner that it protrudes out from the vehicle body in the vertical direction, someone may feel that the design is odd. Therefore, it is common that the space for housing the monitor is greatly limited in the vertical direction. However, according to the above conventional monitoring device, the dimension in the vertical direction is increased. Therefore, serious problems may be encountered when the monitoring device is incorporated into a vehicle.
Further, according to the above conventional monitoring device, the specific structure and adjusting mechanism for obtaining a desired performance and characteristic are not disclosed at all. After all, it can be said that the above patent publication discloses no device that can be put into practical use.
The present invention has been accomplished to solve the above problems of the related art. The present invention provides a very practical monitor for monitoring the periphery of a vehicle characterized in that: the dimension in the vertical direction is small, so that the monitor can be incorporated into a small vehicle without any restrictions; and the performance and characteristics are excellent. The present invention discloses a specific mechanism to realize the monitor for monitoring the periphery of a vehicle.
According to a first aspect of the present invention, there is provided a monitor for monitoring the periphery of a vehicle comprising: a radiating means for radiating waves of light, having an optical system means for removing astigmatic difference of a light source by using a pair of cylindrical lenses, prisms and mirrors; and an optical path changing means including a reflection mirror for reflecting the luminous flux radiated from the radiating means in a direction of the radiated light diffusing means. Since, it is possible to change the optical path while astigmatic difference of the light source is being corrected, the degree of freedom of design is enhanced without being restricted by the position of the radiating means. Accordingly, the dimension of the device in the vertical direction can be easily reduced.
According to a second aspect of the present invention, there is provided a monitor for monitoring the periphery of a vehicle in which the radiated light diffusing means, reflected light converging means, light receiving means and reflecting mirror of the optical path changing means are arranged on the axis of the rotary shaft, and the radiating means is arranged perpendicular to the axis on the same plane as that of the reflecting mirror. Therefore, the dimension of the device in the vertical direction can be remarkably reduced.
According to a third aspect of the present invention, there is provided a monitor for monitoring the periphery of a vehicle, in which the radiated light diffusing means and reflected light converging means are respectively provided with female screws and integrated into one body when locking screws are screwed into the female screws, and the respective angle positions of the screws with respect to the rotary shaft can be adjusted so that the optical axis of the light radiated and the optical axis of the reflected light can become parallel with each other. When the positions of the light receiving optical system and the drive system are adjusted so that they can make a right angle with each other on the horizontal face, the optical axis of light receiving can be adjusted in a desired geometric direction. Next, when the light sending optical system is adjusted so that the optical axis can be parallel with the light receiving optical axis, the light sending optical axis and the light receiving optical axis can be relatively arranged in a geometric arrangement with accuracy, so that the desired performance and characteristic can be provided.
According to a fourth aspect of the present invention, there is provided a monitor for monitoring the periphery of a vehicle, wherein the inner structural components integrated into one body by the frame member are housed in the outer shell. When the inner structural components are integrated into one body by the frame member, the above adjustment work can be easily performed, and further the assembling work can be easily performed. Furthermore, the mechanical strength of the device can be enhanced.
According to a fifth aspect of the present invention, there is provided a monitor for monitoring the periphery of a vehicle, further comprising a light shielding member for preventing a portion of the waves of light radiated and diffused by the radiated light diffusing means from being incident on the light receiving means when the portion of the waves of light are reflected on the inner face of the outer shell or the inner structural components. Due to the foregoing, erroneous detection of the receiving light is prevented. Therefore, it becomes possible to detect an object located in a short distance which tends to be affected by erroneous detection.
According to a sixth aspect of the present invention, there is provided a monitor for monitoring the periphery of a vehicle, in which the angle position of the rotary shaft is precisely detected when the rotary drive means is driven by feedback control at constant angular speed and when the accumulated totals of the clock pulses of the reference signals and a speed difference outputted according to the comparison of the reference signal at this time with the feedback signal, are jointly counted.